Vehicle manufacturers have continually worked to improve impact sensing arrangements and technologies over the past few decades. In general, impact sensing systems continually monitor signals received from sensors located at various points in the vehicle. Using this data, a centralized controller (or controllers in the sensors themselves) evaluates whether the vehicle has been subjected to an impact, whether the impact is indicative of a sufficient impact condition and to what extent, if any, safety systems arranged in the vehicle should be deployed to protect vehicle occupants in response to the impact condition.
The quality of the signals outputted from the various sensors arranged throughout the vehicle affects the reliability and effectiveness of vehicular impact sensing systems. A higher quality signal improves the ability of the controller to differentiate between non-crash impacts to the vehicle (e.g., the impact from a shopping cart hitting a vehicle in a parking lot), inherent sensor noise and crash impacts capable of causing injuries to the vehicle occupants. Hence, the higher the amplitude of the sensor signal (relative to the signal noise), the easier it will be for the controller to effectively evaluate impact conditions.
Another factor that affects the performance of vehicular impact sensing systems is the ability of the sensors to quickly detect impacts and relay that information to the controller. In general, a faster sensor response time gives the controller more time to evaluate the impact signal and more accurately determine whether a safety device should be deployed to prevent occupant harm for a given impact condition.
In addition, conventional impact sensing systems that rely on pressure sensors arrayed within vehicle members and other pre-existing cavities throughout the vehicle have difficulty in measuring pressure associated with crash-related impacts. For example, through-hole features may exist in the front bumper, rear bumper, and/or side doors of vehicles. Although these through-holes may reduce weight in the vehicle and/or provide a wiring conduit for various vehicle components, they also can significantly reduce the ability of pressure sensors to adequately measure pressure associated with a crash-related impact. Furthermore, the pre-existing cavities in some vehicle doors are too large to effectively allow detection of pressure changes indicative of an impact condition.